Anatomical vessel heat sensors

ABSTRACT

Heat sensors can be positioned within the esophagus of a patient so as to monitor temperature changes during ablation procedures in the heart. Some heat sensors can include a wire that defines an extended heat sensing region capable of detecting a change in the local temperature. Some heat sensors can be conformable to an inner surface of the esophageal wall to maintain contact therewith or to be in close proximity thereto.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the benefit under 35 U.S.C. § 119(e) of U.S.Provisional Patent Application No. 61/597,291, titled ESOPHAGEALTEMPERATURE SENSOR, filed on Feb. 10, 2012, the entire contents of whichare hereby incorporated by reference herein.

TECHNICAL FIELD

The present disclosure relates generally to medical heat sensors, andrelates more particularly to heat sensors that can be deployed withinthe esophagus.

BRIEF DESCRIPTION OF THE DRAWINGS

The written disclosure herein describes illustrative embodiments thatare non-limiting and non-exhaustive. Reference is made to certain ofsuch illustrative embodiments that are depicted in the figures, inwhich:

FIG. 1 is a perspective view of an embodiment of a heat sensing system,wherein an embodiment of a heat sensor is shown positioned within apatient that is schematically depicted in cross-section, and wherein theheat sensor is in use during a cardiac ablation procedure;

FIG. 2 is a partial perspective view of a heat sensing assembly portionof the heat sensing system of FIG. 1, which includes the heat sensor ofFIG. 1;

FIG. 3A is a cross-sectional view of the heat sensor of FIG. 1 takenalong the view line 3A-3A in FIG. 2, wherein the heat sensor is shown ina natural or uncompressed state;

FIG. 3B is another cross-sectional view of the heat sensor of FIG. 1,similar to that shown in FIG. 3A, wherein the heat sensor is shown in adisplaced or compressed state, which may also be referred to as acompliance state;

FIG. 4 is a cross-sectional view of the heat sensor of FIG. 1 positionedwithin the patient, taken along the view line 4-4 in FIG. 1;

FIG. 5 is an enlarged view of FIG. 4, taken along the view line 5therein, which includes a schematic depiction of heating of the atrialwall, the esophagus, and the heat sensor;

FIG. 6 is a plot that depicts illustrative heating patterns of differentportions of the esophagus;

FIG. 7 is a flow diagram that depicts an illustrative method of usingthe heat sensing system of FIG. 1;

FIG. 8A is a perspective view of another embodiment of a heat sensingsystem that includes an inflation system for placement or deployment ofthe heat sensor within the patient, wherein an elevation view of theheat sensor is depicted in a packaged or undeployed state within theesophagus of the patient;

FIG. 8B is an enlarged view of the heat sensor and a portion of theinflation system within the esophagus of the patient taken along theview line 8B-8B in FIG. 8A;

FIG. 8C is a cross-sectional view of the heat sensor and the portion ofthe inflation system within the esophagus of the patient taken along theview line 8C-8C in FIG. 8B;

FIG. 9A is an elevation view of the heat sensing system of FIG. 1 beingused in conjunction with the inflation system of FIG. 8A, wherein theheat sensor is depicted in an unpackaged or deployed state;

FIG. 9B is an enlarged view of the heat sensor and a portion of theinflation system within the esophagus of the patient taken along theview line 9B-9B in FIG. 9A;

FIG. 9C is a cross-sectional view of the heat sensor and the portion ofthe inflation system within the esophagus of the patient taken along theview line 9C-9C in FIG. 9B;

FIG. 10A is another elevation view of the heat sensor of FIG. 1 withinthe esophagus of the patient (shown in cross-section) after having beendeployed within the esophagus and the inflation system removed from it,such that the sensor remains in the unpackaged or deployed state and isfurther in a compliance state so as to yield to movement of theesophagus;

FIG. 10B is a cross-sectional view of the heat sensor of FIG. 1 withinthe esophagus of the patient taken along the view line 10B-10B of FIG.10A;

FIG. 11A is an elevation view of another embodiment of a heat sensorcompatible with the heat sensing system of FIG. 8A, wherein the heatsensor is shown prior to being packaged;

FIG. 11B is a cross-sectional view of the heat sensor of FIG. 11A takenalong the view line 11B-11B;

FIG. 12A is a cross-sectional view of the heat sensor of FIG. 11A in apackaged state and positioned within the esophagus of a patient prior todeployment;

FIG. 12B is a cross-sectional view of the heat sensor of FIG. 11A in adeployed state, wherein the heat sensor has been expanded via aninflation fluid;

FIG. 12C is a cross-sectional view of the heat sensor of FIG. 11A in acompliance state in which the inflation fluid is at a lower pressurethan that used to transition the heat sensor to the deployed state;

FIG. 13 is a plot of a pressure profile within the sensor of FIG. 11Aduring different stages of use;

FIG. 14 is an exploded perspective view of another embodiment of a heatsensor compatible with the heat sensing system of FIG. 8A;

FIG. 15 is a plan view of a portion of the heat sensor of FIG. 14;

FIG. 16A, FIG. 16B, and FIG. 16C each depict a different stage of amethod of forming the heat sensor of FIG. 14;

FIG. 17A is a cross-sectional view of the heat sensor of FIG. 14 in apackaged state and positioned within the esophagus of a patient prior todeployment;

FIG. 17B is a cross-sectional view of the heat sensor of FIG. 14 in adeployed state, wherein the heat sensor has been expanded via a balloon;

FIG. 17C is a cross-sectional view of the heat sensor of FIG. 14 in acompliance state in which the balloon has been removed;

FIG. 18 is an exploded perspective view of another embodiment of a heatsensor compatible with the heat sensing systems of FIGS. 1 and 8A;

FIG. 19A is a cross-sectional view of the heat sensor of FIG. 18 in adeployed state and in a compliance state that is positioned within theesophagus of a patient;

FIG. 19B is a cross-sectional view taken along the view line 19B-19B inFIG. 19A;

FIG. 20A is a cross-sectional view of another embodiment of a heatsensor positioned within the esophagus of a patient;

FIG. 20B is another cross-sectional view of the heat sensor of FIG. 20Apositioned within the esophagus of a patient taken along the view line20B-20B in FIG. 20A;

FIG. 21A is a cross-sectional view of another embodiment of a portion ofa heat sensing system that includes a heat sensor that is positionedwithin the esophagus of a patient, wherein the heat sensing systemincludes an esophagus collapsing feature;

FIG. 21B is another cross-sectional view of the portion of the heatsensing system of FIG. 21A showing a balloon inflated into contact withthe inner surface of the esophagus;

FIG. 21C is another cross-sectional view of the portion of the heatsensing system of FIG. 21A showing the esophagus collapsed into contactand/or close proximity to the heat sensor;

FIG. 22 is a cross-sectional view of the esophagus collapsed intocontact and/or close proximity to the heat sensor taken along the viewline 22-22 in FIG. 21C;

FIG. 23 is a perspective view of another embodiment of a heat sensor;

FIG. 24A is a cross-sectional view of the heat sensor of FIG. 23 takenalong the view line 24A-24A in FIG. 23;

FIG. 24B is another cross-sectional view of the heat sensor of FIG. 23taken along the view line 24B-24B in FIG. 23;

FIG. 25A is an elevation view of the heat sensor of FIG. 23 beingintroduced into the esophagus of a patient;

FIG. 25B is another elevation view of a later stage of the heat sensorof FIG. 23 being positioned within the esophagus of the patient;

FIG. 26A is a cross-sectional view of another embodiment of a heatsensor that is similar to the heat sensor of FIG. 23, wherein thecross-sectional view is taken along a view line such as the view line24A-24A in FIG. 23;

FIG. 26B is another cross-sectional view of the heat sensor of FIG. 26A,wherein the cross-sectional view is taken along a view line such as theview line 24B-24B in FIG. 23;

FIG. 27A is an exploded perspective view of another embodiment of a heatsensor;

FIG. 27B is a cross-sectional view of the heat sensor of FIG. 27A;

FIG. 28 is a schematic view of an embodiment of a heat sensing systemthat can include the heat sensor of FIG. 27A;

FIG. 29A is an elevation view of another embodiment of a heat sensorthat is positioned within the esophagus of a patient;

FIG. 29B is a cross-sectional view of the deployed heat sensor of FIG.29A taken along the view line 29B-29B in FIG. 29A;

FIG. 29C is another cross-sectional view of the deployed heat sensor ofFIG. 29A taken along the view line 29C-29C in FIG. 29A;

FIG. 30A is a partial side elevation view of another embodiment of aheat sensor;

FIG. 30B is a cross-sectional view of the heat sensor of FIG. 30A takenalong the view line 30B-30B of FIG. 30A;

FIG. 31A is a partial side elevation view of another embodiment of aheat sensor; and

FIG. 31B is a cross-sectional view of the heat sensor of FIG. 31A takenalong the view line 31B-31B of FIG. 31A.

DETAILED DESCRIPTION

Atrial fibrillation (“AF”) is a heart disease in which electricalimpulses that are normally generated by the sinoatrial node areoverwhelmed by disorganized electrical activity in the atrial tissue,leading to an irregular conduction of impulses to the ventricles thatgenerate the heartbeat. The result is an irregular heartbeat, which maybe intermittent or continuous. In human populations, AF-inducedirregular heartbeat is a significant source of stroke, heart failure,disability, and death.

A number of surgical options are available for treating AF. One approachis widely known as the Cox-Maze III procedure. In this procedure, theleft atrial appendage is excised, and a series of incisions and/orcryolesions are arranged in a maze-like pattern in the atria. Theincisions encircle and isolate the pulmonary veins. The resulting scarsblock the abnormal electrical pathways, improving normal signaltransmission and restoring regular heart rhythm. While its success rateis relatively good, the Cox-Maze III procedure and variations thereofare complex open-heart surgeries, that can require cardiopulmonarybypass, median sternotomy, and endocardial incisions that requiresuturing of the atria. The risks of complications from Cox-Maze III canbe significant.

Some techniques use heating or cooling sources to createimpulse-blocking lesions on the heart by ablation, rather than incision.Other ablation techniques have been developed that use one or more ofincisions, cryoablation, microwave, and unipolar or bipolarradiofrequency (“RF”) energy to create the pattern of lesions achievedin the original Cox-Maze III procedure. For example, certain unipolar RFtechniques have been used for ablation in endocardial procedures.Endocardial ablation can result in perforation of surrounding organs,due mainly to the difficulty of achieving consistent burn penetration.

Some of the more serious complications that can arise from any of theforegoing ablation procedures are those caused by time-dependent, deepheating through excessive heat transfer. A perforation of the atrialwall due to excessive heating can cause permanent structural damage tothe heart, or to the heart and to surrounding tissue. For example,excessive heat transmitted by RF energy or microwaves can permeate thethin wall of the left atrium and fuse it with the esophagus, forming afistula between the two organs. This creates a pathway into the heartfor bacteria from the esophagus, posing a significant risk of infection,endocarditis, systemic sepsis, and mediastinitus outside the heart andin the heart itself. Accordingly, it can be desirable to monitor thetemperature of the esophagus wall, or stated otherwise, to detectchanges to the temperature (e.g., heating or cooling), during certainablation procedures. Such monitoring can assist in early detection ofoverheating (or, in the case of cryoablation, overcooling) of the atrialwall and/or the esophageal wall, which likewise can prevent or reducedamage to the heart and/or esophagus.

Disclosed herein are various embodiments of heat sensing systems andheat sensors that can be used during AF treatments so as to ameliorateor eliminate one or more of problems discussed above. In variousembodiments, the heat sensors can be situated at a position within theesophagus that is nearest the tip of an ablation device, which tip maybe at a position within the heart of the patient. Some heat sensors canhave an extended region capable of detecting a rise (or, in the case ofcryoablation, a fall) in the local temperature at any position withinthat region. In some embodiments, the heat sensors can be configured toconform to an inner surface of the esophageal wall so as to maintaincontact therewith and/or so as to be in close proximity to the ablationdevice without altering the natural conformation of the esophagus. Sucharrangements can permit monitoring of the temperature of the esophagealwall without substantially deforming the wall; for example, withoutmoving the esophageal wall into closer proximity to the ablation site atthe atrial wall. In other or further embodiments, the esophageal wallmay be brought into proximity with (e.g., into contact with) the sensorafter the sensor has been positioned within the esophagus at a desiredlocation. In certain of such embodiments, the esophagus can be collapsedagainst the sensor, and may even be collapsed in a manner so as toprovide additional spacing between the ablation tip and the esophagus.Other embodiments are also disclosed. The foregoing advantages and/orother advantages of various embodiments will be evident from thedisclosure herein.

FIG. 1 is a perspective view of an embodiment of a heat sensing system100 that can be used in any suitable medical procedure. In theillustrated embodiment, the heat sensing system 100 is configured foruse during an AF ablation procedure. For example, a patient 50 canundergo any suitable ablation procedure of the left atrium wall 72 ofthe heart 70 of the patient. Any suitable ablation tool 80 can beintroduced into the left atrium 71, and an ablation tip 82 can bepositioned at or near the atrium wall 72. The ablation tip 82 can beused to create impulse-blocking lesions in the atrium wall 72 in anysuitable manner, such as those described above. For example, in variousembodiments, the tip 82 is configured to impart microwave and/or RFenergy to the atrium wall 72 so as to heat specific regions of the wall,and/or to conduct cryoablation of the atrium wall 72 so as to coolspecific regions of the wall. The ablation tool 80 may also be referredto as a heat source or, for cryoablation procedures, as a coolingsource.

The wall 62 of the esophagus 60 of the patient can be in close proximityto the atrial wall 72 during the ablation procedure. Accordingly, insome instances, the procedure can heat and/or cool the esophageal wall62. As previously discussed, it may be desirable to avoid significanttemperature changes at the esophageal wall 62 so as to minimize orprevent tissue injury and/or perforation of the wall 62 and/or formationof a fistula between the esophagus 60 and the heart 70.

Accordingly, the heat sensing system 100 can be configured to monitor atemperature at the wall 62 of the esophagus 60 and/or to monitor changesin the temperature of the wall 62. In cases of microwave ablation or RFablation, for example, the temperature of the wall 62 may increase,whereas in cases of cryoablation, the temperature may decrease. Itshould be appreciated that apparatus and methods disclosed herein withrespect to the esophagus 60 and the ablation tool 80 that is usedoutside of the esophagus 60 may be used in other contexts. For example,various embodiments may be configured for use in other anatomicalvessels, where heating (or cooling) occurs outside of the vessels or atthe vessel walls. Moreover, various embodiments may be used with othermammalian esophagi and/or other anatomical vessels.

The heat sensing system 100 can include a monitor or controller 102,which may include one or more buttons or actuators 106 that areconfigured to effect one or more operations, such as navigating throughmenus, making selections, or otherwise providing commands. Thecontroller 102 can include a display 104 that is configured to displayinformation in a visually perceivable format. For example, the display104 can comprise a screen of any suitable variety, including thosepresently known and those yet to be devised. For example, the screen 104can comprise a liquid crystal display (LCD) panel. In some embodiments,the screen 104 can be configured to receive information or otherwiseinteract with a medical practitioner. For example, the screen 104 cancomprise a touch screen. The controller 102 can be coupled with a heatsensing assembly 110, so as to communicate therewith, in any suitablemanner. In the illustrated embodiment, the controller 102 and the heatsensing assembly 110 are coupled with each other via a cable 107 havinga connector 108.

Various procedures discussed herein, such as monitoring of temperature,or detection of heating or cooling, can be accomplished via the monitoror controller 102. In some embodiments, the controller 102 can comprisea general-purpose or special-purpose computer, or some other electronicdevice, and at least a portion of the procedures may be embodied inmachine-executable instructions therein. In other embodiments, at leasta portion of the procedures (e.g., various steps or stages thereof) maybe performed by hardware components that include specific logic forperforming the steps or by a combination of hardware, software, and/orfirmware.

The heat sensing assembly 110 can include a heat sensor 120 that isconfigured to be positioned within the esophagus 60 of the patient 50.The heat sensor 120 can be positioned at an end of a catheter 114, whichmay include electrical leads therein to permit communication between thecontroller 102 and the heat sensor 120. The catheter 114 may include aconnector 112 that is configured to interface with the connector 108.The heat sensor 120 can be configured to detect a temperature and/or achange in temperature (e.g., heating or cooling). For example, in someembodiments, the heat sensor 120 comprises one or more electricallyresistive elements that have temperature-dependent properties. In otherembodiments, the heat sensor 120 comprises an array of thermocouples.Other suitable arrangements are also contemplated.

As shown in FIG. 1, in some embodiments, the heat sensor 120 may definea heat sensing zone or sensing region 170 that extends along a sensinglength L_(S). The sensing length L_(S) may be significantly greater thana length L_(A) of a temperature alteration zone or region 124. Having aheat sensing region 170 that exceeds a length of the temperaturealteration zone 124 that may have an altered temperature (e.g.,increased or decreased temperature) during an ablation procedure can aidin ensuring that the heat sensor 120 detects the temperature change, orstated otherwise, detects heating or cooling. Moreover, in someinstances, the heat sensor 120 can be positioned within the esophagus 60such that a portion of the length L_(S) is distal to the position atwhich the ablation tip 82 is closest to the esophagus 60 and anotherportion of the length L_(S) is proximal to the position at which theablation tip 82 is closest to the esophagus 60, such as the position atwhich the atrial wall 72 is closest to the esophagus 60. In variousembodiments, the length L_(A) can be within a range of from about 2centimeters to about 8 centimeters, and the length L_(S) can be greaterthan the length L_(A) and within a range of from about 4 centimeters toabout 10 centimeters. In other or further embodiments, the length L_(S)can be no less than about 2, 4, 6, 8, or 10 centimeters, no greater thanabout 4, 6, 8, or 10 centimeters, or within a range of from about 2 to10, 4 to 10, or 4 to 8 centimeters. In some embodiments, the sensinglength L_(S) can be roughly the same length as a maximum length of theheart 70 of the patient 50. Other sensing lengths L_(S) and temperaturealteration lengths L_(A) are also possible.

The temperature alteration zone 124 can extend through a volume of spaceat an interior of the esophagus 60. For example, in some embodiments,the temperature alteration zone 124 may be substantially conical,frustoconical, or cylindrical, depending on the manner in which heatpropagates through an interior of the esophagus 60 due to a localizedheat source at an exterior of the esophageal wall. In some instances,the temperature alteration zone 124 may be relatively small (althoughintense) near the position of the external heat source and may expandtoward an opposing side of the esophageal wall. The length L_(A) mayalso be referred to as a longitudinal length of the temperaturealteration zone 124, as this length is measured in a directioncorresponding to a longitudinal axis of the esophagus. The heat sensingregion 170 can fully extend through the temperature alteration zone 124.For example, in the illustrated embodiment, and as discussed above, theheat sensor 120 is positioned such that a distal end thereof is distalto the temperature alteration zone 124 and such that a proximal endthereof is proximal to the temperature alteration zone 124.

FIG. 2 depicts the heat sensing assembly 110 in greater detail. In theillustrated embodiment, the connector 112 includes a plurality ofelectrical pins 113, each of which is coupled with an electrical lead115 that extends through the cable or catheter 114 between the connector112 and the heat sensor 120.

The heat sensor 120 can be configured to contact an inner surface of theesophagus 60, as further discussed below. The heat sensor 120 comprisesa support structure 130 that can provide this contact in an electricallyinsulating manner and, in some embodiments, can support other componentsof the heat sensor 120. In the illustrated embodiment, the supportstructure 130 comprises a tube, sleeve, or sheath, although otherarrangements are also possible, as discussed further below. Accordingly,the support structure 130 may also be referred to herein as a sheath forcertain arrangements and/or as an electrically insulating structure. Theterms support structure and electrically insulating structure are usedsynonymously herein. The illustrated sheath 130 comprises an outer layer132, which may also be referred to as a cover or superstrate, and aninner layer 134, which may also be referred to as a base or substrate.

The heat sensor 120 can further include a heat sensing structure 140,which can be supported by the sheath 130. In the illustrated embodiment,the heat sensing structure 140 is sandwiched between and is enveloped orencapsulated by the inner and outer layers 134, 132 of the sheath 130.As further discussed below, the inner and outer layers 134, 132 of thesheath 130 may desirably comprise one or more electrically insulating ordielectric materials so as to electrically shield the heat sensingstructure 140 from one or more electrically conductive substances, suchas saliva, tissue, water, blood and/or other conductive materials withinthe esophagus 60.

Although the inner layer 134 constitutes the substrate and the outerlayer 132 constitutes the superstrate in the illustrated embodiment, itshould be appreciated that the orientation of the substrate and thesuperstrate can be reversed. For example, in some embodiments, the heatsensing structure 140 or other component is originally joined to thesubstrate in at least a temporary fashion, and then the superstrate islaminated, adhered, or otherwise attached to the substrate toencapsulate the heat sensing structure 140. However, other suitabletechniques or methods may be used to encapsulate the heat sensingstructure 140 between the substrate and the superstrate. Moreover, inthe illustrated embodiment, the inner and outer layers 134, 132 aredefined by separate pieces of material that are joined together. Inother embodiments, the inner and outer layers 134, 132 (e.g., thesubstrate and the superstrate) can be formed of a unitary piece ofmaterial that is folded or otherwise formed in a manner thatencapsulates the heat sensing structure 140.

The inner and/or outer layers 134, 132 can be formed of one or morematerials that are not only insulating, but are also capable ofconducting heat. For example, the support structure 130 can beconfigured to permit heat transfer to, from, or both to and from theheat sensing structure 140. In other or further embodiments, the innerand/or the outer layers 134 can comprise a biocompatible material thatcan contact portions of a patient's anatomy without adverse effects.

In the illustrated embodiment, the heat sensing structure 140 comprisestwo separate wires 142, 144, which may also be referred to as tracewires. Each wire 142, 144 has two ends, and each end is electricallycoupled with a separate electrical lead 115 at a connection interface145, which may also be referred to as a junction. In certainembodiments, the wires 142, 144 may be the same as or similar to thoseused in resistance thermometers, which are also known as resistancetemperature detectors or resistive thermal devices (RTDs). In someembodiments, the wires 142, 144 extend over a greater area than standardRTDs, which often may be quite small and are used to measure a discretetemperature on a small area (e.g., no greater than about 1/4 squareinch) of a structure. The wires 142, 144 may comprise any suitablemetallic or other material that exhibits desirable resistanceproperties. For example, in various embodiments, the wires 142, 144 cancomprise platinum, copper, and/or nickel. The wires 142, 144 can have aunique, and repeatable and predictable resistance versus temperature (Rvs. T) relationship and operating temperature range. The R vs. Trelationship is defined as the amount of resistance change of the sensorper degree of temperature change. The predictable change in theresistance of the wires 142, 144 with a change in temperature can beused to detect and monitor heating from the ablation tool 80 within theesophagus 60, as further described below.

Platinum is a noble metal and has a more stable R vs. T relationshipover a larger temperature range, as compared with nickel and copper.Nickel elements have a limited operational temperature range because theamount of change in resistance per degree of change in temperaturebecomes very non-linear at temperatures over 300° C. However, nickel canbe suitable for temperature ranges experienced within the esophagusduring various ablation procedures described herein. Copper also has avery linear resistance to temperature relationship, however, copper canoxidize at moderate temperatures and generally is not as well suited fortemperatures over 150° C. Nevertheless, copper can also be suitable forcertain temperature ranges experienced within the esophagus duringvarious ablation procedures described herein.

Each of the wires 142, 144 can extend continuously in both alongitudinal direction (e.g., the direction of the central axis of theillustrated sensor 120) and in one or more lateral directions that aretransverse to the longitudinal direction (e.g., perpendicular to or anyother direction that is non-collinear with or nonparallel to thelongitudinal direction). For example, in the illustrated embodiment, thewires 142, 144 have portions that extend in the longitudinal direction,which is a substantially vertical direction in the orientation shown inFIG. 2. The wires 142, 144 further extend about the perimeter orcircumference of the illustrated sensor 120. Those portions of the wires142, 144 that extend peripherally or circumferentially may be said toextend in two transverse directions that are perpendicular to thelongitudinal direction. For example, if the longitudinal direction isdefined as the Z-axis of the sensor 120, and if a plane that isperpendicular to the Z-axis includes perpendicular X- and Y-axes, thenit may be said that the wires 142, 144 each extend in the Z-direction(longitudinally) and in both the X- and Y-directions (two lateraldirections that are perpendicular to the longitudinal direction). Statedotherwise, the wires 142, 144 have various portions that includecomponents in each of the X-, Y-, and Z-directions. The wires 142, 144extend in multiple directions to define the heat sensing region 170. Itmay also be said that each wire 142, 144 is fixed to the substrate 134in a circuitous path. The heat sensing region 170 thus extends over afinite area that is significantly greater than a single point. Forexample, thermocouples generally sense temperatures at a single point,which is at a junction of wires that comprise different materials. Incontrast, the heat sensing region 170 defined by the heat sensingstructure 140 can span an area that is much greater than the limitedregion that can be sensed by such thermocouples. In the illustratedembodiment, the heat sensing region 170 extends along the distance L_(S)in the longitudinal direction. The heat sensing region 170 can furtherextend about a majority of a perimeter of the sheath 130. In variousembodiments, the heat sensing region 170 can extend around no less thanabout ⅓, ½, ⅔, or ¾ of a perimeter of the sheath 130. In someembodiments, the heat sensing region 170 can extend about an entirety ofthe perimeter.

The heat sensor 120 can be sensitive to temperature changes that occuranywhere within the heat sensing region 170. For example, in somearrangements, if only a small portion of one of the wires 142, 144 isheated, the resistance of the heated portion will increase, such thatthe total resistance of the heated wire 142, 144 will likewise increase.In some instances, correlation between temperature and resistance of thewire 142, 144 can be used to determine the temperature at the heatedportion of the wire 142, 144. However, in other instances, it may onlybe possible to determine that some amount of heating (or cooling) hasoccurred along at least a portion of the length of the wire 142, 144,although the temperature at that specific portion of the wire may not bedetermined and/or although the exact position along the wire 142, 144 atwhich the heating has occurred may not be determined. In someembodiments, it may be sufficient to determine that a temperature changeof a sufficient magnitude has been effected anywhere within the heatsensing region 170 in order to conclude that damage to the esophagus 60or other bodily structures may occur if ablation continues. Any suitabledetermination based on readings or measurements from the heat sensor 120may be made by the controller 102. In view of functionalities of variousembodiments of the heat sensor 120, the term “heat sensor” issufficiently broad to include sensors and processes that detect a changein temperature, whether that change is an increase or a decrease (e.g.,heating, as an increase in heat, or cooling, as a decrease in heat),even if the sensor does not determine what the temperature is at a givenpoint and/or does not provide information from which the temperature canbe determined. For example, the term “heat sensor” can include a“temperature change sensor,” which is a sensor that is capable ofdetecting a change in temperature (e.g., due to heating or cooling)anywhere within a sensing region of the sensor. The sensor may becapable of detecting such a temperature change, even where the changeoccurs at only a portion of the sensing region. Similarly, the term“heat sensing” is sufficiently broad to include “temperature changesensing,” in which changes in temperature (e.g., heating or cooling) aredetected, even if an exact or specific temperature is not determined.

In some embodiments, multiple wires may be used and arranged in anysuitable pattern so as to determine the position at which temperaturehas changed, as discussed below. However, in some embodiments, theactual position at which heating (or cooling) occurs within theesophagus 60 may not be important, so long as the heat sensor 120 ispositioned to sense any temperature change due to an ablation procedure.That is, so long as any temperature change or heating due to theablation procedure can be determined and monitored by any portion of thesensor 120, the temperature, or temperature change, information obtainedby the heat sensor 120 may be sufficient. Such information can be used,for example, to conclude that the ablation procedure should be at leasttemporarily delayed or halted so as to prevent undesired damage to theesophagus 60 and/or other anatomical structures.

The illustrated embodiment can allow for a rough determination ofwhether one or both semi-cylindrical halves of the sensor 120 areundergoing temperature changes. Each of the two wires 142, 144 defines asubstantially zigzag or serpentine pattern that doubles back on itself.Each wire 142, 144 is confined to one side (e.g., opposing 180-degreeswaths) of a substantially cylindrically shaped sheath 130. It may besaid that the wires 142, 144 define an array, grid, pattern, mesh, orlattice, which provides for a sensitive heat sensing region 170. Otherarrangements of the wires 142, 144 are also possible. The array can beconfigured to provide information regarding a specific region of theheat sensing structure 140. For example, given the particulararrangement of the wires 142, 144 shown in FIG. 2, the resistance of onewire 142, 144 can be compared with that of the other wire 142, 144 so asto determine the differences in heating (or cooling) at one side of thesheath 130 relative to the other side of the sheath 130. In other orfurther embodiments, multiple wires may be positioned at differentlongitudinal positions, such that information may be obtained as to thelongitudinal position of the sensor 120 at which heating takes place.

In other embodiments, the heat sensing structure 140 may comprise asingle wire. In still further embodiments, the heat sensing structure140 may comprise two or more, three or more, or four or more wires. Thewire or wires may be arranged in any suitable configuration so as todefine a relatively large heat sensing region 170. The plurality ofwires may also be arranged as desired in any number of longitudinalpositions and/or radial positions to permit provide informationregarding the specific region or regions of the sensor 120 at whichtemperature changes occur. In some embodiments, the wire or wires mayalso have large openings or spaces 171 between adjacent branchesthereof, such that a width of each space 171 is many times (e.g., 10,100, or 1,000 or more times) greater than a diameter of the wire.Likewise, a surface area of the heat sensing region 170 can be muchlarger than the surface area of one or more electrical wires that definethe heat sensing region 170. For example, in various embodiments, a fullexterior surface of the one or more electrical wires can define a firstsurface area and an outermost boundary of the heat sensing region 170can define a second surface area. In FIG. 2, the first surface area isdefined as the total surface area of the wires 142, 144, and the secondsurface area is defined as the surface area of the cylindrical regionthat extends from the top end of the wires 142, 144 to the bottom end ofthe wires 142, 144 when the heat sensor 120 is in the depictedorientation. In various embodiments, the second surface area defined bythe heat sensing region 170 can be no less than 50, 100, 500, or 1000times the first surface area defined by the wires 142, 144. The largeopenings or spaces may permit the heat sensing structure 140 to be morecompliant, as compared with more compactly spaced wires. However, inother embodiments, the wires may be more tightly compacted, but may berelatively flexible. In either case, the sensing structure 140 may beconfigured to yield to natural movements of the esophagus 60.

In some embodiments, the heat sensor 120 comprises a temperature sensor172. Any suitable temperature sensor may be used, such as, for example,a thermocouple. Accordingly, the temperature sensor 172 may also bereferred to as a thermocouple 172 in reference to the specificembodiment depicted in FIG. 2. The thermocouple 172 can be positionednear a proximal end of the support structure 130, and may be distancedfrom the heat sensing region 170. The thermocouple 172 can be used toobtain a temperature reading of a region of the esophagus 60 that is notexpected to undergo temperature changes due to the ablation procedure.Stated otherwise, the thermocouple 172 can be positioned outside of theheat sensing region 170 to determine a representative temperature of thesubstrate 132 to which it is attached. Although outside of the heatsensing region 170, the thermocouple 172 may nevertheless be in closeproximity to the region 170. In other embodiments, the thermocouple 172may be positioned at an interior of the heat sensing region 170, andthus may also be in close proximity to the heat sensing region 170 inthis manner. The thermocouple 172 can provide a baseline reading oftemperature in the vicinity of the heat sensing region 170. The baselinemay be used to calibrate the heat sensing region 140 in any suitablemanner. The thermocouple 172 may also be referred to herein as areference temperature sensor or as a baseline temperature sensor. Theresistive element heat sensor 120 may be monitored in relation to thereference thermocouple 172. For example, in some arrangements, if theresistive element (e.g., one or more of the wires 142, 144) changes inelectrical resistivity and the reference thermocouple 172 remains stable(e.g., does not change or changes by a relatively small amount), it maybe concluded that the heat sensor 120 is detecting localized heatingwithin the heat sensing region 170 (e.g., at a position along thesensing length L_(S)). In other embodiments, any suitable temperaturesensor other than a thermocouple 172 may be used to determine referencetemperature outside of the heat sensing region 170. In other or furtherembodiments, multiple reference temperature sensors, such as thereference thermocouple 172, may be positioned outside of the heatsensing region 170.

In certain embodiments, the heat sensor 120 includes one or more imagingmarkers 127, 129 for visualization of the heat sensor 120 duringplacement and/or use via fluoroscopy or any other suitable imagingtechnique. In the illustrated embodiment, an imaging marker 127 isplaced at the proximal end of the heat sensor 120 and another imagingmarker 129 is placed at the distal end of the heat sensor 120. Otherarrangements and placements of the one or more imaging markers 127, 129is also possible. Each marker 127, 129 may comprise any suitablesubstance, such as, for example, silver, gold, bismuth, cesium, thorium,tin, zirconium, tantalum, tungsten, and/or lanthanum and/or compoundsthereof. In some embodiments, the markers 127, 129 may be referred to asradiopaque markers. The same or similar makers may be used with any ofthe heat sensors disclosed herein.

With reference to FIGS. 3A and 3B, the heat sensor 120 can be configuredto transition between a natural or uncompressed state (FIG. 3A) and adisplaced or compressed state (FIG. 3B), which may also be referred toas a compliance state. In the illustrated embodiment, the supportstructure 130 comprises an elastically resilient and flexible materialthat is biased toward the orientation shown in FIG. 3A, and the supportstructure 130 can be displaced or deformed to other orientations, suchas that shown in FIG. 3B, upon application of forces thereto (e.g., thecompression forces F_(C)). Upon removal or discontinuance of thedisplacement or deforming forces, the support structure 130 can returnto its uncompressed state. In certain embodiments, the biasing forcesthat arise within the support structure 130 when deformed are relativelysmall in comparison to the forces applied by the esophagus 60, such thatthe support structure 130 is very compliant with respect to theesophagus 60. Accordingly, in some embodiments, the bias is sufficientto maintain the support structure 130 in an expanded state so as tocontact and/or be in close proximity to an inner wall of the esophagus60 without deforming the esophagus 60, or without substantiallydeforming the esophagus 60. For example, the support structure 130 canbe sufficiently compliant to permit the esophagus 60 to be in asubstantially relaxed or collapsed state, and will not expand theesophagus 60 into closer proximity to the atrial wall 72 of the heart70, yet the support structure tracks, follows, conforms to, complieswith, or accords with an inner surface of the esophagus 60. Such anarrangement is depicted in FIGS. 3B-5, as discussed further below, andmay be referred to as a compliance state or as a tracking, following,conformance, or according state. As used herein, the term “withoutsubstantially deforming” includes situations in which no deformationtakes place, but also includes situations in which negligibledeformation takes place. For example, the support structure 130 maypress against an inner surface of the esophagus 60 and may slightlycompress the esophageal wall and/or may slightly displace or deform theesophageal wall. However, such deformations will not be significant, andmay only move the esophageal wall marginally closer to the ablationsite. In some instances, “substantial deformation” can be defined asincreasing or decreasing one or more of the maximum transverse width(e.g., maximum diameter) and the minimum transverse width (e.g., minimumdiameter) of the esophagus by an amount greater than 20 percent of theoriginal magnitude thereof.

In the illustrated embodiment, the support structure 130 comprises atube or sheath, which may be substantially cylindrical when in theuncompressed state, as shown in FIG. 3A. When positioned within theesophagus 60, the support structure 130 may be compressed into an oblongor ovoid configuration, such as that depicted in FIGS. 3B-5. If theesophagus 60 expands or becomes more cylindrical under normal or naturalconditions, or upon other removal of the compressive forces F_(C) (suchas removal of the heat sensor 120 from the esophagus 60), the supportstructure 130 can move toward or return to the uncompressedconfiguration. The support structure 130 thus may be configured tomaintain contact with, or otherwise maintain close proximity to, theinner surface of the esophagus 60. Maintaining contact or closeproximity between the support structure 130 and the inner wall of theesophagus 60 can permit effective thermal transfer from the esophagealwall to the heat sensor 120 (e.g., particularly to the heat sensingresistive wires 142, 144). The esophagus 60 is depicted in a flattenedcylindrical state, but any natural state of the esophagus iscontemplated, including, for example, highly convex and/or convoluteorientations.

As previously discussed, the support structure 130 may be flexible,malleable, or readily conformable so as to be displaced, compressed,transformed, altered, or reshaped into an orientation that tracks,follows, conforms to, complies with, or accords with an inner surface ofthe esophagus 60. Moreover, in the illustrated embodiment, the supportstructure 130 is resiliently flexible and is biased toward a naturalconfiguration (e.g., a cylinder) that provides a degree of structuralrigidity to the support structure 130. However, in other embodiments,the support structure 130 may not be biased toward a natural shape, andmay instead be even more compliant, or stated otherwise, may be flaccid,limp, or slack. Certain of such embodiments may be pressed toward oragainst the interior wall of the esophagus 60 via additional structuralfeatures, such as a balloon, and may even be maintained against theinterior wall via these structural features. In other or furtherembodiments, contact may be maintained between the support structure 130and the esophagus 60 via one or more of surface tension (e.g., due tomoisture on the esophagus wall), adhesives, and/or other suitable fixingelements. Certain of such alternative embodiments are discussed furtherbelow. As previously mentioned, the support structure 130 may alsoexhibit dielectric and/or heat conducting properties. In variousembodiments, a support structure 130 having any of the foregoingproperties can comprise one or more biocompatible materials, such asbiocompatible plastics, such as, for example, one or more ofpolyethylene (PE), polypropylene (PP), nylon, or polyvinyl chloride(PVC). A thickness of the support structure 130 can be within a range offrom about 0.001 inches to about 0.040 inches, or may be no greater thanabout 0.001, 0.002, 0.003, 0.004, 0.005, 0.010, 0.020, 0.030, or 0.040inches.

The support structure 130 can be flexible, resiliently flexible, and/orcompliant, e.g., in manners just described. Similarly, the encapsulatedheat sensing structure can be flexible, resiliently flexible, and/orcompliant. Accordingly, the heat sensor 120 can be flexible, resilientlyflexible, and/or compliant. Flexibility of the heat sensor 120 may beabout a single axis, in some embodiments, or the flexibility may beabout multiple axes in other embodiments. For example, in someembodiments, the heat sensor 120 may extend longitudinally and may beflexible about any axis that is perpendicular to a longitudinal axis ofthe heat sensor 120. In this manner, the illustrated embodiment can bebent in any direction and may conform to longitudinal curves of theesophagus. In other or further embodiments, the heat sensor 120 can beflexible about the longitudinal axis itself and/or about any axisparallel thereto. For example, in the illustrated embodiment, the heatsensor 120 is also flexible in this manner, such that an outer surfaceof the heat sensor 120 is capable of conforming to an inner periphery ofthe esophagus 60. Stated otherwise, the heat sensor 120 can be flexiblealong its longitudinal length and/or in directions that are transverseto the longitudinal length. Accordingly, in various embodiments, thesupport structure 130 can be configured to conform to curves or bendsalong a length of the esophagus and/or to an inner periphery of theesophagus at any lateral cross-section of the esophagus.

With continued reference to FIGS. 3A and 3B, in various embodiments, theheat sensing region 170 can extend about a significant portion of alateral cross-section of the heat sensor 120. The cross-sectional viewof the heat sensor 120 shown in FIGS. 3A and 3B may generally bereferred to as a “perimeter” of the heat sensor 120. In the illustratedembodiment, the perimeter is substantially circular in FIG. 3A and issubstantially ovoid in FIG. 3B. The wires 142, 144 can create a bulge inthe inner and outer layers 132, 134 of the sheath 130. The bulge may beexaggerated in the views shown in FIGS. 3A and 3B for purposes ofillustration, as a diameter of the wires 142, 144 may be substantiallysmaller, in proportion to a diameter of the sheath 130, than what isshown in FIGS. 3A and 3B. In various embodiments, a diameter of thewires 142, 144 is no greater than about 0.0001, 0.001, or 0.010 inches,whereas a diameter of the sheath 130 can be within a range of from about0.375 inches to about 1.25 inches, or no less than about 0.4, 0.5, 0.75,1.0, or 1.25 inches.

As can be seen in FIGS. 3A and 3B, the wires 142, 144 extend aboutnearly the full perimeter of the sheath 130. In various embodiments, oneor more wires extend along, or about, no less than ¼, ⅓, ½, ⅔, or ¾ of aperimeter of the sheath 130. Stated otherwise, the heat sensing region170 can extend circumferentially about no less than ¼, ⅓, ½, ⅔, or ¾ ofa perimeter of the sheath 130. As the sheath 130 may generally conformto an interior surface of the esophagus, the heat sensing region 170likewise may extend circumferentially about no less than ¼, ⅓, ½, ⅔, or¾ of, or about no less than a majority of, an inner perimeter of theesophagus 60.

FIGS. 4 and 5 illustrate use of the heat sensor 120, and more generally,the heat sensing system 100, during an ablation procedure. In theillustrated embodiment, an ablation tool 80 delivers energy to theatrial wall 72 via an ablative tip 82. The energy causes heating of theatrial wall 72, as desired, but also can cause heating of the wall 62 ofthe esophagus 60. The heating may be more intense at an outer surface 63of the esophagus wall 62, as compared with an inner surface 64 thereof,as the esophageal tissue can be insulating. In the illustratedarrangement, the wire 144 is positioned so as to more readily sense achange in temperature, as compared with the wire 142, although the wire142 may nevertheless sense a less dramatic change in temperature.Cooling of the atrial wall 72 may proceed in a similar manner incryoablation procedures.

FIG. 6 depicts a plot 200 of a temperature profile 201 detected by theheat sensor 120 during an ablation procedure. More particularly, theplot depicts the temperature profile of the inner surface 64 of theesophagus 60, as detected by the wire 142 of the heat sensor 120, duringthe ablation procedure. In addition to the temperature profile 201, theplot 200 also includes, for reference purposes, a temperature profile202 of the external wall 63 of the esophagus 60, as well as a baselineprofile 203 that depicts the normal esophagus temperature. Comparison ofthe profiles 201, 202 illustrates how the esophagus can insulate theheat sensor 120 such that temperature changes are less pronounced at theposition of the heat sensor 120. Accordingly, it can be desirable forthe heat sensor 120 to be sensitive to small temperature changes.

In certain embodiments, the heat sensing system 100 triggers an alarmwhen the temperature profile 201 reaches or exceeds a threshold valueV_(T). The alarm can signify to the surgeon that damage to the esophagusand/or other bodily structures may result if ablation continues. Thealarm may be provided in any suitable manner, such as via an audiblesound and/or a visible warning on the display 104 (see FIG. 1). In otheror further embodiments, ablation may automatically be discontinued whenthe threshold value V_(T) is reached. For example, the controller 102can direct that power no longer be supplied to the ablation tool 80 whenthe threshold value V_(T) is reached. In still other or furtherembodiments, the alarm may be triggered and/or ablation automaticallydiscontinued when the rate of change of the temperature profile 201reaches or exceeds a threshold rate. The actual value of the thresholdvalue V_(T) may be different than what is schematically represented inFIG. 6.

FIG. 7 depicts an illustrative method 220 of using the heat sensingsystem 100 of FIG. 1, such as during the ablation procedure depicted inFIG. 1. At least some of the stages of the method may be accomplishedvia the controller 102 and/or interaction between the controller 102 andthe heat sensing assembly 110. At stage 230, the resistance of one ormore wires 142, 144 is measured. At stage 232, a fixed period of time,which may also be referred to as a scan time, is permitted to transpire.In various applications, the scan time can be no greater than 0.01seconds, 0.1 seconds, or 1 second. At stage 234, the resistance of theone or more wires 142, 144 is again measured. At stage 236, the rate ofchange in wire resistance is calculated. For example, stage 236 cancomprise determining the difference in the wire resistances obtained atstages 230 and 234, and dividing the same by the fixed scan time toobtain the rate of change of the wire resistance. At decision stage 238,it is determined whether the rate of change meets or exceeds a thresholdvalue. If it does not, then the process cycles back to stage 232. If thethreshold value is met or exceeded, then the alarm is triggered at stage240. Stage 240 may additionally or instead include automaticallydiscontinuing the ablation. In some embodiments, the controller 102includes electrical noise filters and/or is configured for redundantsignal monitoring to prevent false alarms and/or undesireddiscontinuance of ablation.

Other methods of using the heat sensing system 100 are alsocontemplated, including variations of the method 220. For example, insome embodiments, measurements of the wire resistance may besubstantially continuous. Accordingly, stage 232, at which an incrementof time is permitted to transpire between subsequent measurements ofwire resistance, may be eliminated. The rate of change of wireresistance may be calculated by comparing any desired subset ofmeasurements, taking into account the amount of time that transpiredbetween the measurements.

FIG. 8A illustrates another embodiment of a heat sensing system 300 thatcan resemble the heat sensing system 100 described above in certainrespects. Accordingly, like features are designated with like referencenumerals, with the leading digits incremented to “3.” Relevantdisclosure set forth above regarding similarly identified features thusmay not be repeated hereafter. Moreover, specific features of the system300 may not be shown or identified by a reference numeral in thedrawings or specifically discussed in the written description thatfollows. However, such features may clearly be the same, orsubstantially the same, as features depicted in other embodiments and/ordescribed with respect to such embodiments. Accordingly, the relevantdescriptions of such features apply equally to the features of thesystem 300. Any suitable combination of the features and variations ofthe same described with respect to the system 100 can be employed withthe system 300, and vice versa. This pattern of disclosure appliesequally to further embodiments depicted in subsequent figures anddescribed hereafter, wherein the leading digits may be furtherincremented.

The heat sensing system 300 can include the heat sensor 120 discussedabove. The heat sensing system 300 can further include an inflationsystem 301 configured to deploy the temperature sensor 120 within theesophagus 60 of the patient 50. In some embodiments, the heat sensingsystem 300 includes a monitor 302, such as the monitor 102 discussedabove, which may include additional functionalities, such as the abilityto sense, monitor, control, and/or display the pressure of an inflationfluid.

The inflation system 301 can include any suitable inflation device 305,such as, for example, those that are commonly used to deploy stents orthe like. In some embodiments, the inflation device 305 can include asyringe that delivers inflation fluid to a fluid path 313 and canpressurize the fluid within the fluid path 313. It is noted that theterm “fluid” may refer to one or more liquids and/or gases. The fluidpath 313 can be incorporated into a catheter 314, such as the catheter114 discussed above. For example, in some embodiments, the fluid path313 includes one or more lumens that pass through at least a portion ofthe catheter 114. In other embodiments, the fluid path 313 may beseparate from the catheter 114. For example, in some embodiments, aconduit that is separate from the catheter 114 may define the fluid path313. The separate conduit may be movable relative to the catheter 114,and may be placed within the esophagus 60 separately from the catheter114 and/or separately extracted from the esophagus 60.

In some embodiments, the inflation device 305 is configured to becontrolled by the controller 302. For example, in some embodiments, apressure sensor (e.g., a pressure transducer) can be couple to the fluidpath 313 and can be in electrical communication with the controller 302.Based on pressure readings from the pressure sensor, the controller 302can adjust the inflation device 305 to increase or decrease the pressurewithin the fluid path 313.

FIGS. 8B and 8C illustrate the heat sensor 120 in a packaged,undeployed, folded, rolled, or compressed state, which facilitatesinsertion of the heat sensor 120 into the esophagus 60. In theillustrated embodiment, the heat sensor 120 includes a support structure130 that has a substantially cylindrical natural configuration; however,the support structure 130 is folded and rolled into a low-profileconfiguration and is maintained in this configuration via a removablepackaging sheath 377.

The inflation system 301 includes an inflation assembly 380 that ispositioned at an interior of the heat sensor 120. The inflation assembly380 includes an expandable balloon 382 and a wire sheath 384. The wiresheath 384 defines a lumen 385 that is sized to pass over a guide wire375. A cavity 387 is provided between the balloon 382 and the wiresheath 384, which can be filled and pressurized with an inflation fluid386. At the stage depicted in FIGS. 8A-8C, only a small amount ofinflation fluid 386 is present within the balloon 380. In otherembodiments, no inflation fluid 386 may be present within the balloon380 at the illustrated stage.

Placement of the heat sensor 120 into the position shown in FIGS. 8A-8Ccan proceed as follows. The guide wire 375 is inserted into theesophagus 60 and advanced to a desired position, which may besubstantially below the position at which the esophagus 60 is closest tothe heart 70. The packaged heat sensor 120 and inflation assembly 380are then advanced over the guide wire 375, with the wire sheath 384sliding or otherwise passing over the guide wire 375. The packagingsheath 377 may then be removed.

FIGS. 9A-9C illustrate a subsequent stage of placement of the heatsensor 120 within the esophagus 60. At this stage, the inflation device305 is used to introduce additional inflation fluid 386 into the balloon382, thereby causing the balloon 382 to expand. The balloon 382 may beexpanded sufficiently far, or by a sufficient amount, to bring thesupport structure 130 into contact with and/or otherwise into closeproximity to the inner surface 64 of the esophagus 60. The heat sensor120 may be said to be in a deployed or expanded state in FIGS. 9A-9C.

FIGS. 10A and 10B illustrate a subsequent stage of placement of thesensor 120, in which the heat sensor 120 is in the desired position andis in an operational state, so as to be used during an ablationprocedure. The inflation assembly 380 has been removed from an interiorof the heat sensor 120, and the esophagus 60 has returned to its relaxedor natural orientation. In the illustrated embodiment, the supportstructure 130 is biased outwardly so as to maintain contact with and/orclose approximation to the inner surface 64 of the esophagus 60. Inother or further embodiments, the support structure 130 may maintaincontact with and/or close approximation via surface tension or othersuitable methods or manners of adhesion, as discussed above. In theillustrated configuration, the heat sensor 120 is still in the deployedor expanded state. However, as it is also now free to be moved bymovement of the esophagus 60, or otherwise conform to the esophagus 60,it may also be referred to as being in a conformance, tracking,following, or according state. The support structure 130 may besufficiently compliant or flimsy to remain in close proximity to theinner surface 64 of the esophagus substantially without deforming theesophagus. The heat sensor 120 may detect temperature changes and/orotherwise operate in manners such as described above.

In other embodiments, the inflation assembly 380 may remain at theinterior of the heat sensor 120 during the ablation procedure. Apressure of the expansion fluid within the balloon 382 can be adjustedto maintain the heat sensor 120 in contact with the esophagus withoutexpanding the esophagus. Rather, the pressure can be adjusted to a levelat which the heat sensor 120 tracks the natural movement of theesophagus. Such a tracking state is similarly discussed below withrespect to FIG. 12C.

In still other embodiments, the heat sensor 120 can be deployed withinthe esophagus 60 without the inflation assembly 380. For example, insome embodiments, the heat sensor 120 can be positioned within theesophagus 60 over a guidewire while being retained in the packagingsheath 377. Or in other or further embodiments, the heat sensor 120 canbe selectively positioned within the esophagus 60 and released from theend of a cannula. In either case, whether upon removal of the sheath 377or release from the cannula, a resilience of the wall material of theheat sensor 120 can cause the sensor to unroll, unfold, or otherwiseexpand and position itself against the wall 62 of the esophagus 60. Insome embodiments, although the sensor 120 is sufficiently resilient toexpand so as to conform to an inner surface 64 of the esophagus 60, itmay nevertheless track the movement of the esophagus and/or notsubstantially expand the esophagus.

FIGS. 11A and 11B illustrate another embodiment of a heat sensor 420,which is compatible with the heat sensing system 300 of FIG. 8A. Theheat sensor 420 can function in a manner similar to the inflationassembly 380 discussed above, and thus may also be referred to as aninflation assembly. For example, the heat sensor 420 can include asupport structure 430 similar to the support structure 130 discussedabove, but which can also function in a manner similar to the balloon182 discussed above. The support structure 430 can define at least aportion of a closed cavity 487 into which inflation fluid can bereceived to expand the support structure 430 into close proximity to(e.g., contact with) an inner wall of the esophagus. The heat sensor 420can be assembled to a catheter 414, such as the catheter 314 discussedabove.

The illustrated embodiment of the heat sensor 420 includes two wires442, 444, such as the wires 142, 144 (only wire 442 is shown in FIG. 11Afor clarity). Other embodiments can include more or fewer wires inmanners such as previously discussed. The illustrated wires 442, 444 canbe connected to electrical leads 415 at connection interfaces 445. Theheat sensor 420 can include a thermocouple 472, such as the thermocouple172 described above. The wires 442, 444 may be sandwiched between innerand outer dielectric layers 432, 434 of the support structure 430, andthe heat sensor 420 can further include a wire sheath 484 at an interiorof the support structure 430. As shown in FIG. 11A, the proximal anddistal ends of the support structure 430 can be attached to the wiresheath 484 via proximal and distal fluid-tight seals 489. Accordingly,the closed cavity 487 can be defined by the support structure 430 andthe wire sheath 484, which are sealed to each other via the fluid-tightseals 489.

FIGS. 12A-12C depict various stages of positioning the heat sensor 420within the esophagus 60 of the patient. At the stage depicted in FIG.12A, the heat sensor 420 is in a packaged state within a packagingsheath 477. In some embodiments, the wire sheath 484 is advanced over aguide wire 475 into the position shown in FIG. 12A. In the illustratedembodiment, the guide wire 475 is removed before progressing tosubsequent stages of delivery. In other embodiments, the guide wire 475may remain in place during greater amounts of the placement and/or heatsensing procedures. At the stage depicted in FIG. 12B, an inflationfluid 486 is introduced into the cavity 487 and thereby expands thesupport structure 430 into contact and/or close proximity with theesophagus 60. The heat sensor 420 is thus in an expanded or deployedstate. The guide wire 475 has been removed at this stage. At the stagedepicted in FIG. 12C, the inflation fluid 486 remains within the supportstructure 430. However, the pressure of the inflation fluid 486 has beenreduced, as compared with the inflation fluid at the stage of FIG. 12B.The reduced pressure can allow the support structure 430 to comply withthe natural configuration of the esophagus 60. Accordingly, theconfiguration shown in FIG. 12C may be referred to as a conformance,tracking, following, or according state. As will be apparent from thediscussion above regarding the inflation device 305, in someembodiments, the pressure of the inflation fluid 486 can be controlledby the inflation device 305. In some embodiments, the inflation device305 can be controlled manually. In other embodiments, the inflationdevice 305 can be controlled by a controller in manners such asdescribed above, and thus a pressure of the inflation fluid 486 can becontrolled by the controller.

In some embodiments, expanding the support structure 430 by an amountsufficient to displace a portion of the esophagus 60, such as in themanner depicted in FIG. 12B, can aid in achieving a tight fit or contactbetween the support structure 430 and the esophagus. For example, thisinflation stage can allow the support structure 430 to adhere to theinner surface 64 of the esophagus 60, such as by surface tension, by anadhesive coated on the exterior of the support structure 430, and/or inany other suitable manner. Thereafter, when the pressure of theinflation fluid 486 is reduced, the support structure 430 can maintainits close proximity with the inner surface 64 of the esophagus. Such aclose proximity can aid with thermal transfer from the esophagus 60 tothe heat sensing wires 442, 444. In some arrangements, it can bedesirable to ensure that the inflation pressure is reduced to an amountsuch as depicted in FIG. 12C prior to commencing ablation of the atrialwall 72, as the unexpanded or slack orientation of the esophagus 60 mayprovide greater spacing between the atrial wall 72 and the esophagus 60.

FIG. 13 depicts a plot 490 of the pressure of the inflation fluid 486 asa function of time. The three deployment stages depicted in FIGS.12A-12C are identified in the plot 490 as “Sensor Insertion,” “SensorDeployment,” and “Sensor in Compliance State.” During sensor insertion,only atmospheric pressure may be present within the support structure430. During deployment, the inflation fluid 486 can increase thepressure to a value of P₁. Thereafter, the inflation fluid 486 can bereduced to a tracking pressure P₂. The tracking pressure P₂ can besufficient to maintain contact between at least a portion of the supportstructure 430 and the esophagus wall, and yet not substantially deformthe esophagus wall.

FIGS. 14 and 15 illustrate another embodiment of a heat sensor 520. Theheat sensor 520 includes a heat sensing structure 540, which is definedby two wires 542, 544. More or fewer wires may be used, in manners suchas described above. The heat sensor 520 further includes a referencetemperature sensor 572. The reference temperature sensor 572 may also bereferred to herein as a thermocouple 572, although any suitabletemperature sensor may be used. The wires 542, 544 and the thermocouple572 can be laminated or sandwiched between two or more layers of supportmaterial 532, 534, which may also be referred to as a superstrate 532and a substrate 534, respectively. The superstrate 532 and the substrate534 can cooperate to form a support structure 530. In FIG. 15, thesuperstrate 532 is not shown. The support structure 530 can besubstantially flat or planar when in a relaxed or natural state.

As discussed above with respect to the temperature sensor 172, thetemperature sensor 572 can be configured to track a temperature that isrepresentative of an entirety of the substrate 534 and/or superstrate532 to which it is attached. The wires 542, 544 can be configured tosense localized heating.

FIGS. 16A-16C depict an illustrative method for assembling the heatsensor 520. In some embodiments, two separate wires 542, 544 and areference thermocouple 572 (see FIG. 15) are positioned on one side of athin flexible plastic film 534. A second thin flexible plastic film 532is positioned opposite the first film 534, and the components are placedbetween two heat plates 596, 598, which cause heat lamination andbonding of the films 532, 534 to each other with the components capturedinside and sealed around the perimeter. In some methods, non-stick films592, 594 are placed between the heat plates 596, 598 and the films 532,534. The non-stick films 592, 594 may comprise, for example, sheets ofpolytetrafluoroethylene. The heat plates 592, 594 are approximatedtogether under a load of any suitable amount and for a suitable durationuntil the thin films 532, 534 adhere to each other. Other methods ofcontaining, capturing, or encapsulating the wires 542, 544 between thethin films 532, 534, or providing a dielectric barrier between thesensing wires 532, 534 and the esophagus 60, are contemplated, such as,for example, one or more of adhesives, plastic coatings, or mechanicalseals. However, in some embodiments, lamination of one or more wiresbetween sheets of plastic can be particularly useful where the wires arenot amenable to being preformed to a predetermined shape (e.g., due to asmall diameter).

FIGS. 17A-17C depict various stages of positioning the heat sensor 520within the esophagus 60 of the patient. At the stage depicted in FIG.17A, the heat sensor 520 is in a packaged state within a packagingsheath 577. At the stage depicted in FIG. 17B, an inflation assembly 580is expanded so as to move the support structure 530 into contact and/orclose proximity with the esophagus 60. The heat sensor 520 is thus in anexpanded or deployed state at this stage. At the stage depicted in FIG.17C, the inflation assembly 580 has been removed. In the illustratedembodiment, opposing side ends of the support structure 530 overlap oneanother when the sensor 520 has been positioned within the esophagus 60.Such an arrangement can allow for the heat sensor 520 to be used withany of a variety of patients whose anatomies differ, such that theiresophagi define differently sized inner perimeters. For example, insmaller esophagi, the opposing side ends of the support structure 530may overlap to a greater degree, whereas in larger esophagi, theopposing side ends of the support structure 530 may not overlap. In anyof the foregoing instances, whether or not the opposing side ends of thesupport structure 530 overlap, the support structure may be said to forma tube, sleeve, or sheath, which can extend along at least a portion ofan inner perimeter of the esophagus. In various embodiments, the rolled,coiled, or curved support structure 530 may cover no less than about ¼,⅓, ½, ⅔, or ¾ of, or no less than a majority of, the inner perimeter ofthe esophagus, and in instances where the side ends abut one another oroverlap, can cover an entirety of the inner perimeter. In each case, alateral cross-section of the support structure 530, such as that shownin FIG. 17C, can be said to depict the lateral perimeter of the supportstructure 530. Stated otherwise, the term “perimeter” does notnecessarily refer to a closed loop, and can define a lateral length(e.g., arc length) of a non-closed tube, sleeve, or sheath structure.

In instances where the side ends overlap, a width of the supportstructure 530, as measured between opposing side edges of the supportstructure 530, may exceed the value of the perimeter (e.g., thecircumference) of the inner surface of the esophagus. In somearrangements, overlapping side ends, such as those depicted in FIG. 17C,may allow for the heat sensor 520 to yield more readily to movements ofthe esophagus 60, as compared with a closed tube. As can be appreciatedfrom the drawings, in the illustrated embodiment, the heat sensor 520 isflexible about at least a longitudinal axis. In some embodiments, theheat sensor 520 is also flexible about axes that are perpendicular tothe longitudinal axis, such that the heat sensor 520 can conform to anylongitudinal curvature of the esophagus.

FIG. 18 illustrates another embodiment of a heat sensor 620. The heatsensor 620 includes a heat sensing structure 640, which includes aplurality of thermocouples 672 that are spread out in an array. The heatsensing structure 640 can define a heat sensing region 670. Eachthermocouple 672 can be configured to sense a temperature at a pointwithin the heat sensing region 670. Any suitable arrangement ofelectrical leads 615 can run from the sensing region of eachthermocouple 672 to a connector or other device, such as the connector112 described above, so as to interface with a monitor (e.g., thecontroller 102). The thermocouples 672 and associated leads 615 can besandwiched between two layers of support material 632, 634, which formsa support structure 630. The support structure 630 can be substantiallyplanar when in a natural or relaxed state.

FIGS. 19A and 19B illustrate the heat sensor 620 positioned within theesophagus 60. The support structure 630 can be coiled such that opposingside ends of the support structure 630 overlap one another. The array ofthermocouples 672 can be used to obtain numerous temperaturemeasurements so as to monitor the portion of the esophagus 60 that isadjacent to the heat sensing region 670.

The heat sensor 620 can be delivered into the esophagus 60 in anysuitable manner. For example, in some embodiments, the heat sensor 620is introduced into the esophagus 60 in a packaged state in which theheat sensor 620 is rolled or coiled into a small cross-sectional profilewithin a packaging sheath, such as the packaging sheath 377 discussedabove.

FIGS. 20A and 20B illustrate another embodiment of a heat sensor 720.The heat sensor 720 includes a heat sensing structure, such as the heatsensing structure 540 shown in FIG. 18, which includes a plurality ofthermocouples 772 that are spread out in an array. The thermocouples 772and their associated electrical leads can be sandwiched between twolayers of support material 732, 734, which forms a support structure730. Unlike the support structure 630, the support structure 730 mayform a closed loop, which is sized so as to rest against an innersurface of the esophagus 60. In the illustrated embodiment, the heatsensor 720 can resemble the inflatable heat sensor 420 depicted in FIGS.11A-12C, and may include a wire sheath 784. The support structure 730may be maintained in a conformance operational mode by slightlypressurized inflation fluid 786 in manners such as described above. Inother embodiments, the heat sensor 720 may be separate from theinflation fluid 786 so as not to directly contact the fluid. Forexample, in some embodiments, the heat sensor 720 may be urged intoplace by a separate expandable balloon, such as the balloon 382discussed above. Any other suitable deployment techniques andproperties, such as those discussed above, are possible for the heatsensor 720.

FIGS. 21A-21C and 22 illustrate another embodiment of a distal portionof a heat sensing assembly 1410, which can be used with any suitableheat sensing system described herein. The heat sensing assembly 1410 isshown within the esophagus 60 of a patient at different stages ofdeployment. The heat sensing assembly 1410 includes a heat sensor 1420of any suitable variety, including any of the heat sensors disclosedherein. In the illustrated embodiment, the heat sensor 1420 particularlyresembles, or may be the same as, the heat sensor 520 described abovewith respect to FIGS. 14-17C. As further discussed hereafter, in somearrangements, the heat sensor 1420 may include a support structure 1430that may define a substantially planar or flat configuration whendeployed within the esophagus, rather than being curled into a generallytubular shape so as to expand into close proximity to the esophagealwall in manners such as described above with respect to the heat sensor520. Accordingly, in some embodiments, the support structure 1430 may bethicker and/or less pliable (e.g., more rigid) than the curled supportstructures of certain embodiments of the heat sensor 520. In otherembodiments, the support structure 1430 may be pliable in manners suchas discussed above, and may readily comply with, conform to, or track ashape of the esophagus. As shown in FIG. 22, in the illustratedembodiment, the support structure 1430 includes two layers 1432, 1434that are joined together so as to encapsulate two wires 1442, 1444.

The heat sensing assembly 1410 can include any suitable device or systemfor collapsing the esophagus about the heat sensor 1420. Collapsing theesophagus 60 so as to bring the inner wall 64 into close contact and/orclose proximity with the heat sensor 1420 can increase thermal transferbetween the wall and the heat sensor 1420. In some instances, collapsingthe esophagus 60 may space the esophageal wall further from the heart,which may also reduce heating of the wall during an ablation procedure.Such an arrangement may, in some instances, facilitate construction ofthe heat sensor 1420, given that a larger range of pliability orrigidity may be suitable for the support structure 1430 as compared withsome other arrangements, as previously discussed. Such a system may bedescribed as being configured to collapse the esophagus into contact orclose proximity to the heat sensor 1420, rather than expanding orotherwise deploying the heat sensor 1420 into contact or close proximityto the esophagus.

In the illustrated embodiment, the device for collapsing the esophaguscomprises an inflatable balloon 1480 having an evacuation lumen 1481. Aproximal portion of the evacuation lumen 1481 is housed in a catheter1414. Although the evacuation lumen 1481 is shown extending through theinflatable balloon 1480 in the illustrated embodiment, the evacuationlumen 1481 can be separate from the balloon 1480 in other embodiments.In some embodiments, the catheter 1414 further includes a fluid path(not shown), such as the fluid path 313 discussed above, through whichan inflation fluid can be delivered to and removed from the balloon1480. In further embodiments, the catheter 1414, or a separate catheter,can house electrical leads to and from the heat sensor 1420 and/or oneor more additional fluid paths or fluid conduits to and from the heatsensor 1420, depending on the type of heat sensor. In the illustratedembodiment, the catheter 1414 houses four electrical leads (not shown),consisting of two electrical leads for each of the resistive wires 1442,1444.

As shown in FIG. 21A, the heat sensing assembly 1410 can be introducedinto the esophagus 60 with the balloon 1480 in a collapsed state. Oncethe heat sensor 1420 is in a desired position, inflation fluid may beused to expand the balloon 1480 into contact with the inner wall 64 ofthe esophagus 60, as shown in FIG. 21B. The contact may provide afluid-tight seal. As shown in FIG. 21C, air and/or fluids about heatsensor 1420 can be evacuated via the evacuation lumen 1481 to bring theesophagus into contact and/or close proximity to the heat sensor 1420.In the illustrated embodiment, a single balloon 1480 is used in theevacuation/collapsing procedure, and the balloon 1480 is positionedproximally relative to the heat sensor 1420. In other embodiments, theballoon 1480 may be positioned distally relative to the heat sensor1420. In still other embodiments, the heat sensing assembly 1410 mayinclude two balloons that are positioned proximally and distallyrelative to the heat sensor 1420. In such embodiments, the portion ofthe esophagus that is between the expanded balloons can be evacuated.

In various embodiments, the heat sensor 1420 may resemble, or be thesame as, other heat sensors described herein. For example, the heatsensor 1420 may resemble any of the heat sensors 120, 420, 520, 620, 720described above and/or any of the heat sensors 1520, 1520′, 1620, 1720,1820, 1920 described below. The heat sensing assembly 1410 can includeany such heat sensor and one or more esophageal collapsing mechanisms,such as the balloon 1480. Additionally, the catheter 1414 and/or one ormore additional catheters can accommodate additional wire leads and/orfluid paths, depending on the type of heat sensor that is used. Forexample, for heat sensors such as the heat sensor 1620 discussed below,the catheter 1414 can house, in addition to the four electrical leadsdiscussed above, two fluid conduits through which heat transfer fluidcan be cycled through the heat sensor.

FIGS. 23 through 25B depict another embodiment of a heat sensor 1520that is compatible with various heat sensing systems disclosed herein.In some embodiments, the heat sensor 1520 may be positioned along thedistal end of a catheter 1514. The heat sensor 1520 can be configured toreadily conform to the inner wall of the esophagus. For example, theheat sensor 1520 can be extremely compliant, or stated otherwise, canhave very little rigidity. In the illustrated embodiment, the heatsensor 1520 comprises a tube 1533 having a structural integrityresembling a thread, a string, or wet noodle. That is, the tube 1533 canbe readily moved into any desired orientation, and in some embodiments,may not have a significant intrinsic orientation bias. For example, thetube 1533 may readily respond to external forces (e.g., gravity, surfacetension, adhesion forces) without internally counteracting those forces.

With reference to FIG. 25A, in some embodiments, the heat sensor 1520has an outer diameter and outer perimeter that are significantly smaller(e.g., smaller by a factor of no less than 5 times) than the innerdiameter and inner perimeter of the esophagus. The heat sensor 1520 canbe introduced into the esophagus 60 of a patient over a guide wire 1575.The guidewire 1575 may substantially define a straight line during thepositioning stages. As shown in FIG. 25B, the guidewire 1575 may beretracted from the tube 1533. As the guidewire 1575 is retracted, adistal tip of the guidewire 1575 may trace out a generally spiralpattern relative to the esophageal wall 64. As the distal tip of theguidewire 1575 is further retracted in the proximal direction, segmentsof the tube 1533 can successively adhere and conform to the esophagealwall 64, such as by surface tension. When the guidewire 1575 is fullyretracted from the heat sensor 1520, the tube 1533 can define a heatsensing region 1570 that extends along a longitudinal length of theesophagus 60 and extends along an inner periphery of the esophagus 60.In some arrangements, a practitioner can control a density of the tube1533 within the heat sensing region 1570. For example, in some instanceswhere greater sensitivity within the heat sensing region 1570 may bedesired for a given tube 1533, the tube 1533 may be spiraled tightlysuch that adjacent loops are relatively close together. In otherinstances where less sensitivity within the heat sensing region 1570 maybe sufficient for the same tube 1533, the tube 1533 may have a looserspiral, such that adjacent loops are further apart.

In other embodiments, the tube 1533 may be applied to the esophagealwall 64 in any suitable arrangement. For example, rather than a regularhelical shape, such as shown in FIG. 25B, the tube 1533 may be appliedin any other regular pattern, such as, for example, a serpentinepattern. In still other embodiments, an irregular shape or pattern maybe used. For example, the tube 1533 may be permitted to assume a jumbledor squiggled shape that covers a swath of the inner esophageal wall 64.In various embodiments, the tube 1533 may be situated within theesophagus so as to extend circumferentially around no less than about ¼,⅓, ½, ⅔, or ¾ of, or no less than a majority of, an inner perimeter ofthe esophagus.

As shown in FIGS. 24A and 24B, the tube 1533 can comprise a supportstructure 1530 that carries a heat sensing structure 1540. In theillustrated embodiment, the support structure 1530 comprises asubstantially cylindrical outer layer 1532 and a substantiallycylindrical inner layer 1534 that are concentric. The heat sensingstructure 1540 is a single resistance wire 1542 that is laminatedbetween the inner and outer layers 1534, 1532. The wire 1542 may be ofany suitable variety, such as those discussed above, and can increase inresistance when heated. In other embodiments, more wires may be used. Inother or further embodiments, the heat sensing structure 1540 caninclude fluid channels instead of or in addition to the heat sensingwire 1542. In the illustrated embodiment, the wire 1542 extends distallyat one side of the tube 1533 along substantially the full length of thetube 1533. As shown in FIG. 24B, the wire 1542 is doubled back betweenthe inner and outer layers 1534, 1532 at the distal end of the tube1533, and then extends proximally at an opposite side of the tube 1533along substantially the full length of the tube 1533. Other arrangementsare also contemplated.

With continued reference to FIGS. 24A and 24B, the inner layer 1534 ofthe support structure 1530 can define a lumen 1585 through which theguidewire 1575 can pass. In some embodiments, the lumen 1585 is onlyused with the guidewire 1575. However, in other embodiments, the lumen1585 may additionally or alternatively be used to transport heattransfer fluid (such as the heat transfer fluid 1661 discussed belowwith respect to FIG. 28). A heat transfer structure 1505 thus mayinclude the lumen 1585. In the illustrated embodiment, the heat transferfluid (such as the heat transfer fluid 1661) can flow through the lumen1585 and drain into the esophagus 60 at the distal end of the lumen1585.

As previously mentioned, in some embodiments, the support structure 1530can be configured to readily conform to the inner wall of the esophagus.For example, the support structure 1530 can be elongated in alongitudinal direction, or along a longitudinal axis, and can beextremely flexible or compliant in any direction that is transverse tothe longitudinal axis. However, in some embodiments, it may be desirablefor the elongated support structure 1530 to be relatively orsubstantially inextensible along the longitudinal axis. Such anarrangement may be desirable, for example, where the trace wire 1542 isthin, fragile, and/or otherwise susceptible to breakage. In suchinstances, elongation of the support structure 1530 could result inbreakage of the trace wire 1542, in the illustrated embodiment, or oneor more trace wires 1542 in embodiments that include multiple tracewires. Such breakage would reduce the sensitivity of the heat sensor1520 or render it inoperable. In various embodiments, the supportstructure 1530 has a modulus of elasticity that is sufficiently high toprevent significant elongation in the longitudinal direction. Forexample, in some embodiments, the modulus of elasticity is greater thanthat of polypropylene.

FIGS. 26A and 26B illustrate another embodiment of a heat sensor 1520′that is similar to the heat sensor 1520, except that the heat sensor1520′ is configured to cool the esophagus without draining the heattransfer fluid (e.g., the heat transfer fluid 1661) into the esophagus.Stated otherwise, the heat sensor 1520′ includes a closed-loop heattransfer structure 1505.

The heat sensor 1520′, when viewed in perspective, can closely resemblethe heat sensor 1520 that is depicted in FIG. 23, except that theopening at the distal end of the tube is smaller and is shaped as asemicircle. The distal opening of the heat sensor 1520′ corresponds tothe distal end of the guidewire lumen 1585 that is depicted in FIGS. 26Aand 26B. The guidewire lumen 1585 can extend from the proximal end tothe distal end of the heat sensor 1520′ such that the guidewire 1575 canextend fully through the heat sensor 1520′.

The heat sensor 1520′ can include a heat transfer structure 1505, whichcan include two heat transfer lumens 1552, 1554. The heat transferlumens 1552, 1554 can extend from the proximal end of the heat sensor1520′ to a position that is near, but proximal to, the distal end of theheat sensor 1520′. The lumens 1552, 1554 can be in fluid communicationwith each other at this distal position, as shown in FIG. 26B, but canbe separate from each other along the remainder of the length of theheat sensor 1520′, as shown in FIG. 26A. The distal ends of the lumens1552, 1554 can be capped, such that only a small channel 1555 betweenthe distal ends of the lumens 1552, 1554 provides the fluidcommunication between the two lumens 1552, 1554. Accordingly, in someembodiments, the heat transfer fluid (e.g., the heat transfer fluid1661) can travel distally through the lumen 1552, and can return in aproximal direction through the lumen 1554.

Like the heat sensor 1520, the heat sensor 1520′ can further include awire 1542. Accordingly, each heat sensor 1520, 1520′ can be included ina system that is configured for both heat sensing and heat transfer. Forexample, where the heat sensors 1520, 1520′ are used in ablationprocedures that tend to heat the esophagus, the heat sensors 1520, 1520′can sense heating of the esophageal wall via the wire 1542. The heatsensors 1520, 1520′ can also cool the esophageal wall so as to reduce orprevent damage thereto by channeling heat transfer fluid through theirrespective heat transfer structures 1505 (i.e., the lumen 1585 for theheat sensor 1520 or the lumens 1552, 1554 for the heat sensor 1520′).Systems and methods in which the heat sensors 1520, 1520′ can be usedare discussed more fully below with respect to FIG. 28.

FIGS. 27A-28 depict another embodiment of a heat sensor 1620. Like theheat sensors 1520, 1520′, the heat sensor 1520 can include both a heatsensing structure 1640 and a heat transfer circuit or heat transferstructure 1605. As a further similarity, the heat sensing structure 1640includes wires 1642, 1644 from which changes in resistive properties canbe detected, whereas the heat transfer structure 1605 is configured tochannel a heat transfer fluid along a fluid circuit or fluid path (e.g.,a series of interconnected conduits). The heat sensor 1620 thus may besaid to include an active heat transfer (e.g., cooling) circuit.

The heat sensor 1620 comprises a support structure 1630. In theillustrated embodiment, the support structure 1630 comprises a laminateof three layers 1632, 1634, 1637 of material. The layers 1632, 1634,1637 may be of any suitable material, such as those discussed above withrespect to the support structure 130. The layer 1634 may also bereferred to as a substrate, the layer 1632 may also be referred to as asuperstrate, and the layer 1637 may also be referred to as a heattransfer layer.

In the illustrated embodiment, the heat sensor 1620 resembles the heatsensor 520 described above with respect to FIGS. 14-17C. Moreover, thatportion of the heat sensor 1620 that closely resembles the heat sensor520 can operate in the same manners as the heat sensor 520 describedabove. However, in addition to a laminate structure defined by thelayers 1632, 1634 that encapsulates the resistive wires 1642, 1644 and athermocouple 1672, the heat sensor 1620 includes the further layer 1637,which at least partially defines the heat transfer structure 1605. Inparticular, the lamination layer 1637 includes a series of grooves 1609that cooperate with the middle layer 1632 to define fluid channels 1641,1649 through which heat transfer fluid 1661 can be cycled.

As shown in FIG. 28, the heat sensor 1620 can be used in a heat sensingand heat transferring system 1600, which can include a controller 1602,a fluid source 1660, a pump 1662, and a fluid recovery receptacle 1670.In some embodiments, the controller 1602 can be in electrical or othercommunication with the pump 1662 so as to control operation of the pump1662. For example, the controller 1602 may adjust a speed of the pump1662. In other embodiments, the pump 1662 may be operated independentlyof the controller 1602 (e.g., may be operated manually). In otherembodiments, the pump 1662 may not be used, such as when the fluidsource 1660 comprises pressurized fluid (e.g., pressurized air). Thecontroller 1602 can resemble the controller 102 discussed above, and maybe capable of carrying out methods and processes discussed above andhereafter. For example, the controller 1602 may include hardware and/orsoftware that is programmed, or programmable, to control one or more ofthe components of the heat sensing system 1600 to carry out variousprocesses. Communicative connections between the controller 1602 and thevarious components of the heat sensing system 1600 are not shown in FIG.28.

The fluid source 1660 can provide a supply of heat transfer fluid 1661.The heat transfer fluid 1661 can comprise any suitable fluid. It may bedesirable for the heat transfer fluid 1661 to be non-toxic or otherwisesuitable for ingestion by a patient in the event of a leak or where theheat transfer fluid 1661 is drained into the esophagus of the patient.However, in some embodiments, it may be most desirable for the heattransfer fluid 1661 to have particular heating characteristics, such asa desired specific heat, and precautions may be made where such fluidsmay potentially harmful if ingested. In some embodiments, the recoveredheat transfer fluid 1661 is cycled from the fluid recovery receptacle1670 back to the fluid source 1660. For example, in some embodiments,these components may comprise a common fluid reservoir.

The pump 1662 can move heat transfer fluid 1661 through the heat sensingsystem 1600. In particular, in the illustrated embodiment, the pump 1662moves heat transfer fluid 1661 from the fluid source 1660, through theheat sensor 1620, and to the fluid recovery receptacle 1670. Anysuitable fluid connections between the various components of the heatsensing system 1600 are possible, and are schematically represented byarrows that show the direction of fluid flow.

In other embodiments, rather than having a fluid recovery receptacle1670, the heat transfer fluid 1661 may instead be drained after it exitsthe heat sensor 1620. In certain of such embodiments, used heat transferfluid 1661 may drain into the esophagus and may proceed to the patient'sstomach. In certain of such embodiments, the heat transfer fluid 1661may comprise water, air, saline solution, or some other ingestiblefluid. In other embodiments the used heat transfer fluid 1661 may bedrained or vented at an exterior of the patient. For example, when theheat transfer fluid 1661 comprises compressed air, the used air may bevented to a surrounding environment or atmosphere after it has passedthrough the system 1600.

One or more catheters, such as those described above, may be used tocouple the heat sensor 1620 with the heat transfer fluid circuit and/orthe controller 1602. For example, the one or more catheters may includelumens or fluid paths for conducting the heat transfer fluid 1661 to andfrom the heat sensor 1620 and/or they may include electrical leads thatextend between the heat sensor 1620 and the controller 1602.

In operation, the controller 1602 can determine when the resistance ofone or more of the wires 1642, 1644 increases (or decreases, as incryoablation) by an amount that merits the signaling of a warning (e.g.,to a practitioner) and/or the automatic termination of the ablationprocedure. The pump 1662 can draw heat transfer fluid 1661 from thefluid source 1660 and urge the heat transfer fluid 1661 through the heattransfer structure 1605 of the heat sensor 1620 and into the fluidrecovery receptacle 1670. In some arrangements, the pump 1662establishes at a steady flow rate. In certain of such arrangements, thecontroller 1602 determines that equilibrium is reached before ablationcommences. For example, the controller 1602 may determine that theresistance in the wires 1642, 1644 has reached a constant value afterthe heat transfer fluid 1661 has coursed through the heat transferstructure 1605 for a sufficient time to have cooled the esophageal wallto a steady temperature. Accordingly, in some embodiments, the heatsensor 1620 is capable of reducing or preventing damage to the esophagusby simultaneously sensing heating of the esophagus so as to terminate anablation procedure before damage is done and cooling the esophagus toreduce the risk of burning from the outset.

In some embodiments, the heat sensor 1620 is configured to curl in amanner similar to the heat sensor 520, as depicted in and described withrespect to FIGS. 17A-17C, and can conform to and/or track naturalmovements of the esophagus. In other embodiments, the heat sensor 1620may be deployed into a substantially flat state and the esophagus may becollapsed about the heat sensor 1620 in any suitable manner, such asthat described above with respect to FIGS. 21A-30. In some embodiments,the outer layer 1634 of the support structure 1630, which is in contactwith the resistive wires 1642, 1644, may be positioned closest to theablation site.

FIGS. 29A-29C illustrate another embodiment of a heat sensor 1720 whichcan be used in any suitable heat sensing and heat transferring system,such as the system 1600 (with modifications, as discussed below). Theheat sensor 1720 can closely resemble the heat sensor 420 discussedabove, and can include a similar support structure 1730 and heat sensingstructure 1740. In particular, the heat sensing structure 1740 caninclude one or more resistive wires 1742. In the illustrated embodiment,a single resistive wire 1742 is used, which extends about a fullperiphery of an inner layer of the support structure 1730 to form a twinhelical pattern, as schematically shown in FIG. 29A. Other patterns orconfigurations are possible. The wire 1742 is electrically connected toelectrical leads 1715, 1716 at either end thereof.

The heat sensor 1720 can be positioned at the end of a catheter 1714,which can include the electrical leads 1715, 1716 and fluid channels1741. The heat sensor can include a wire sheath 1784 that defines alumen 1785 through which a guidwire can extend. The catheter 1714 candefine a proximal portion of the lumen 1785. The support structure 1730and the wire sheath 1784 can cooperate to define an inflatable cavity1787.

An inflation fluid 1786 can be introduced into the inflatable cavity1787 to expand the support structure 1730 into contact with and/or closeproximity to the inner wall 64 of the esophagus 60 in manners such asdescribed above with respect to FIGS. 12A-12C. Accordingly, FIG. 29Bmay, in some instances, resemble an deployment stage such as thatdepicted in FIG. 12C, and the heat sensor 1720 may be in a conformance,tracking, following, or according state in which the heat sensor 1720conforms to the natural shape of the esophagus substantially withoutdisplacing the esophagus. In some embodiments, the inflation fluid 1786can comprise a heat transfer fluid such as described above, which may beconfigured to counteract the effects of an ablation procedure on theesophageal wall. For example, the inflation fluid 1786 can be cooled forheat-producing ablation procedures (or it may be heated forcryoablation). The inflation fluid 1786 may be circulated through theinflatable cavity 1787 during the ablation procedure so as to assistwith heat exchange. For example, the inflation fluid 1786 may becontinuously supplied to the cavity 1787 via one fluid conduit 1741 ofthe catheter 1714 and continuously drained from the cavity 1787 via theother fluid conduit 1741 of the catheter 1714. In some embodiments, theheat sensing and heat transfer system in which the heat sensor 1720operates includes a controller, which may monitor the pressure of theinflation fluid 1786 and, in some arrangements, maintain the pressure ata substantially constant value during an ablation procedure.

FIGS. 30A and 30B depict another embodiment of a heat sensor 1820 thatis compatible with various heat sensing systems described herein. Theheat sensor 1820 includes a support structure 1830 to which a heatsensing structure 1840 is mounted. In the illustrated embodiment, thesupport structure 1830 includes a core 1834 and a sleeve 1832 that areaffixed to each other, such as by heat shrinking, lamination, or anyother suitable method. The core 1834 may be solid and/or flexible in atleast one direction that is transverse to a longitudinal axis of theheat sensor 1820. The sleeve 1832 encapsulates the heat sensingstructure 1840, which includes two resistive wires 1842, 1844. Any othersuitable number and arrangement of the wires is contemplated. In theillustrated embodiment, two branches of each wire 1842, 1844 extend instraight lines that are parallel to a longitudinal axis of the heatsensor 1820. The wire branches are angularly spaced about the core 1834and are angularly offset from each adjacent branch by about 90 degrees.Such a symmetrical arrangement can aid in sensing heating near thesensor 1820, regardless of the rotational orientation of the sensor.

The heat sensing structure 1840 defines a heat sensing region 1870 thatis coextensive with the wires 1842, 1844. In some embodiments, asensitivity of the heat sensing region 1870 may be increased by usingadditional wires. For example. a greater density of wires (e.g., withangular offsets between adjacent wires of no greater than about 15, 30,45, 60, or 75 degrees) can provide a more noticeable and/or quickerresponse of the heat sensor 1840, as it can ensure that one or more wirebranches will be close to region of the esophagus that is being heated,regardless of the angular orientation of the heat sensor 1840 within theesophagus.

FIGS. 31A and 31B depict another embodiment of a heat sensor 1920 thatresembles the heat sensor 1820 and is compatible with various heatsensing systems described herein. The heat sensor 1920 also includes asupport structure 1930 having a core 1934 and a sleeve 1932 within whicha heat sensing structure 1940 is encapsulated. However, in theillustrated embodiment, the heat sensing structure 1940 includes asingle resistive wire 1942. The heat sensing structure 1940 can providea heat sensing region 1970 that can have the same dimensions (e.g.,length, width, girth, etc.) as the heat sensing region 1870 discussedabove. However, due to the configuration of the wire 1942, the heatsensing region 1970 may be more sensitive. For example, in theillustrated embodiment, the wire 1942 includes a first branch that issubstantially collinear with a longitudinal axis of the heat sensor1920. However, a second branch of the wire 1942 is wound about the core1932 in a relatively tight helix. The second branch thus provides agreater “wire density” within the heat sensing region 1970 than ispresent in the heat sensing region 1870 depicted in FIG. 38A. Thegenerally symmetrical arrangement of the wire 1942 can permit the heatsensor 1920 to have a relatively consistent sensitivity to heating,regardless of a rotational orientation of the heat sensor 1920.

As with the heat sensors 1520, 1520′ discussed above, in someembodiments, the support structures 1830, 1930 are flexible in at leasta first direction that is transverse to a longitudinal direction of theheat sensor in at least the heat sensing region 1870, 1970. However, infurther embodiments, the support structures 1830, 1930 can besubstantially inextensible in the longitudinal direction. Suchlongitudinal stiffness can protect the wires 1842, 942 from damage thatmay be caused by pulling forces in the longitudinal direction. Suchproperties of the support structures 1830, 1930 can permit the heatsensors 1820, 1920 to be purposefully shaped during insertion into theesophagus and/or can allow the heat sensor to conform to the shape ofthe esophagus (e.g., a specific contour of the anatomy).

As previously mentioned, while the drawings and written description havefocused on illustrative devices, systems, and methods related to AFablation procedures, it is to be understood that embodiments may be usedin any other suitable context. Moreover, it will be understood by thosehaving skill in the art that changes may be made to the details of theabove-described embodiments without departing from the underlyingprinciples presented herein. For example, any suitable combination ofvarious embodiments, or the features thereof, is contemplated.

Any methods disclosed herein comprise one or more steps or actions forperforming the described method. The method steps and/or actions may beinterchanged with one another. In other words, unless a specific orderof steps or actions is required for proper operation of the embodiment,the order and/or use of specific steps and/or actions may be modified.

References to approximations are made throughout this specification,such as by use of the terms “about” or “approximately.” For each suchreference, it is to be understood that, in some embodiments, the value,feature, or characteristic may be specified without approximation. Forexample, where qualifiers such as “about,” “substantially,” and“generally” are used, these terms include within their scope thequalified words in the absence of their qualifiers. For example, wherethe term “substantially planar” is recited with respect to a feature, itis understood that in further embodiments, the feature can have aprecisely planar orientation.

Reference throughout this specification to “an embodiment” or “theembodiment” means that a particular feature, structure or characteristicdescribed in connection with that embodiment is included in at least oneembodiment. Thus, the quoted phrases, or variations thereof, as recitedthroughout this specification are not necessarily all referring to thesame embodiment.

Similarly, it should be appreciated that in the above description ofembodiments, various features are sometimes grouped together in a singleembodiment, figure, or description thereof for the purpose ofstreamlining the disclosure. This method of disclosure, however, is notto be interpreted as reflecting an intention that any claim require morefeatures than those expressly recited in that claim. Rather, as thefollowing claims reflect, inventive aspects lie in a combination offewer than all features of any single foregoing disclosed embodiment.

The claims following this written disclosure are hereby expresslyincorporated into the present written disclosure, with each claimstanding on its own as a separate embodiment. This disclosure includesall permutations of the independent claims with their dependent claims.Moreover, additional embodiments capable of derivation from theindependent and dependent claims that follow are also expresslyincorporated into the present written description. These additionalembodiments are determined by replacing the dependency of a givendependent claim with the phrase “any of the preceding claims up to andincluding claim [x],” where the bracketed term “[x]” is replaced withthe number of the most recently recited independent claim. For example,for the first claim set that begins with independent claim 1, claim 3can depend from either of claims 1 and 2, with these separatedependencies yielding two distinct embodiments; claim 4 can depend fromany one of claim 1, 2, or 3, with these separate dependencies yieldingthree distinct embodiments; claim 5 can depend from any one of claim 1,2, 3, or 4, with these separate dependencies yielding four distinctembodiments; and so on.

Recitation in the claims of the term “first” with respect to a featureor element does not necessarily imply the existence of a second oradditional such feature or element. Elements specifically recited inmeans-plus-function format, if any, are intended to be construed inaccordance with 35 U.S.C. § 112(f). Embodiments of the invention inwhich an exclusive property or privilege is claimed are defined asfollows.

1-100. (canceled)
 101. A heat sensing system comprising: a heat sensorthat comprises: a heat sensing wire formed of a single continuousone-piece wire having a resistivity that varies with temperature, theheat sensing wire extending along a continuous path that defines a heatsensing region; a first connection interface at a first end of the heatsensing wire at a first end of the continuous path; a second connectioninterface at a second end of the heat sensing wire at a second end ofthe continuous path, the first and second connection interfaces beingthe only connection interfaces in electrical contact with the heatsensing wire; and an encapsulation covering the heat sensing wire, theencapsulation being configured to electrically isolate the heat sensingwire from an electrically conductive substance at an interior of ananatomical vessel when the heat sensor is deployed within the vessel,and the encapsulation being configured to permit heat transfer to, from,or both to and from the heat sensing wire, wherein the encapsulation isconfigured to transition between a compressed state in which theencapsulation has a first cross-sectional profile and an expanded statein which the encapsulation has a second cross-sectional profile that islarger than the first cross-sectional profile, the encapsulationcomprising an outer surface area that is the same whether theencapsulation is in the compressed state or in the expanded state,wherein each of the heat sensing wire and the encapsulation is flexibleto permit the heat sensing region defined by the heat sensing wire toconform to an inner surface of the anatomical vessel when the heatsensor is deployed within the anatomical vessel; and a controllercoupled with the heat sensor, wherein the controller is configured todetect that heating of the heat sensing region at any location along theheat sensing wire has occurred due to changes to an overall electricalresistance of the heat sensing wire.
 102. The heat sensing system ofclaim 101, wherein the first and second connection interfaces areconnected to respective first and second electrical leads via which theheat sensor can be electrically coupled with the controller.
 103. Theheat sensing system of claim 101, wherein the heat sensor furthercomprises a reference temperature sensor positioned in proximity to theheat sensing region, wherein the reference temperature sensor isconfigured to detect a reference temperature and communicate with thecontroller, wherein the controller is configured to monitor thereference temperature, and wherein the controller is configured todetect that the heating of the heat sensing region at any location alongthe heat sensing wire has occurred by monitoring the changes to theoverall electrical resistance of the heat sensing wire in relation tothe reference temperature.
 104. The heat sensing system of claim 101,wherein the encapsulation of the heat sensor comprises a substrate thatcomprises a solid core and further comprises a superstrate thatcomprises a tubular structure that sheaths the core.
 105. The heatsensing system of claim 101, wherein the encapsulation is resilientlyflexible with an intrinsic bias toward the expanded state.
 106. The heatsensing system of claim 101, wherein the encapsulation is flexible, butnot resiliently flexible, such that the encapsulation readilytransitions between a compressed state and an expanded state, yet isintrinsically unbiased relative to each of the compressed and expandedstates.
 107. The heat sensing system of claim 101, wherein thecontroller is further configured to activate an alarm when a temperatureis detected by the controller that reaches or exceeds a threshold value,wherein a change in the temperature is related to the overall electricalresistance of the heat sensing wire.
 108. The heat sensing system ofclaim 101, wherein the controller is further configured to monitor thechanges to the electrical resistance of the heat sensing wire.
 109. Theheat sensing system of claim 101, wherein the controller is furtherconfigured to determine a rate of change of a temperature profile thatis monitored by the controller, wherein the rate of change is determinedby measuring the changes to the overall electrical resistance of theheat sensing wire over time.
 110. A heat sensing system comprising: aheat sensor that comprises: a heat sensing wire formed of a singlecontinuous one-piece wire having a resistivity that varies withtemperature, the heat sensing wire extending along a continuous paththat defines a heat sensing region; a first connection interface at afirst end of the heat sensing wire at a first end of the continuouspath; a second connection interface at a second end of the heat sensingwire at a second end of the continuous path, the first and secondconnection interfaces being the only connection interfaces in electricalcontact with the heat sensing wire; and an encapsulation covering theheat sensing wire, the encapsulation being configured to electricallyisolate the heat sensing wire from an electrically conductive substanceat an interior of an anatomical vessel when the heat sensor is deployedwithin the vessel, and the encapsulation being configured to permit heattransfer to, from, or both to and from the heat sensing wire, whereinthe encapsulation is configured to transition between a delivery statein which the heat sensing region has a first configuration and adeployed state in which the heat sensing region has a secondconfiguration that is compliant to a wall on the anatomical vessel, theencapsulation comprising an outer surface area that is the same whetherthe encapsulation is in the delivery state or in the deployed state; anda controller configured to couple with the heat sensor, wherein thecontroller is configured to detect that heating of the heat sensingregion at any location along the heat sensing wire has occurred due tochanges to an overall electrical resistance of the heat sensing wire.111. The heat sensing system of claim 110, wherein at least a portion ofthe heat sensor is disposed in a spiral pattern while in the secondconfiguration.
 112. The heat sensing system of claim 111, wherein thespiral pattern is configured to extend along an inner periphery of theanatomical vessel along a longitudinal length of the anatomical vessel.113. The heat sensing system of claim 110, wherein the heat sensingregion is substantially linear in the first configuration.
 114. The heatsensing system of claim 110, wherein the controller is furtherconfigured to monitor the changes to the electrical resistance of theheat sensing wire.
 115. The heat sensing system of claim 110, whereinthe controller is further configured to determine a rate of change of atemperature profile that is monitored by the controller, wherein therate of change is determined by measuring the changes to the overallelectrical resistance of the heat sensing wire over time.
 116. A heatsensing system comprising: a heat sensor that comprises: a heat sensingwire formed of a single continuous one-piece wire having a resistivitythat varies with temperature, the heat sensing wire extending along acontinuous path that defines a heat sensing region; a first connectioninterface at a first end of the heat sensing wire at a first end of thecontinuous path; a second connection interface at a second end of theheat sensing wire at a second end of the continuous path, the first andsecond connection interfaces being the only connection interfaces inelectrical contact with the heat sensing wire; and a first electricallead coupled to the first end of the heat sensing wire at the firstconnection interface; a second electrical lead coupled to the second endof he heat sensing wire at a the second connection interface; and asupport structure comprising a core and a sleeve, wherein at least aportion of the heat sensing wire is disposed between the core and thesleeve, the sleeve being configured to electrically isolate the portionof the heat sensing wire from an electrically conductive substance at aninterior of an anatomical vessel when the heat sensor is deployed withinthe vessel, and the sleeve being configured to permit heat transfer to,from, or both to and from the portion of the heat sensing wire, whereinthe support structure is flexible in at least one direction that istransverse to a longitudinal axis of the support structure; and acontroller configured to couple with the heat sensor, wherein thecontroller is configured to detect that heating of the heat sensingregion at any location along the portion of the heat sensing wire hasoccurred due to changes to an overall electrical resistance of the heatsensing wire.
 117. The heat sensing system of claim 116, wherein thecore is solid.
 118. The heat sensing system of claim 116, wherein thecore comprises at least a portion of the first or the second electricallead.
 119. The heat sensing system of claim 116, wherein the heat sensorfurther comprises a second heat sensing wire, wherein each of the heatsensing wires extends longitudinally along the support structure. 120.The heat sensing system of claim 116, wherein the controller is furtherconfigured to determine a rate of change of a temperature profile thatis monitored by the controller, wherein the rate of change is determinedby measuring the changes to the overall electrical resistance of theheat sensing wire over time.